How to insert an element into a identified element in xslt? - xslt

Question

I have XML-file with complex hierarchical structure, which I copy with document fileName.xml. I want to insert a new element into other element. The target element calculating based on input file with concat('b_',$id).
For example fileName.xml:
<root>
<transform id="b_0">
<transform id="b_1">
<transform id="b_2">
<transform id="b_3"/>
<transform id="b_4"/>
</transform>
</transform>
</transform>
</root>
This is example of result document:
<root>
<transform id="b_0">
<transform id="obj_1"/>
<transform id="b_1">
<transform id="b_2">
<transform id="b_3">
<transform id="obj_2"/>
</transform>
<transform id="b_4"/>
</transform>
</transform>
</transform>
</root>
The pattern of my xslt code:
<xsl:variable name="transforms" select="document('fileName.xml')"/>
<xsl:variable name="table" select="."/>
<xsl:template match="tr">
<xsl:variable name="param" select="$table//tr/td[2]"/>
<xsl:variable name="id" select="concat('b_',$param)"/>
<xsl:copy-of select="$transforms"/>
<xsl:copy>
<Transform>
<xsl:attribute name="id"><xsl:value-of select="concat('obj_', position())"/></xsl:attribute>
<xsl:apply-templates select="$transforms/transform[#id = $id]"/>
</Transform>
</xsl:copy>
</xsl:template>

Answer 1

First of all, it is difficult to understand what you are trying to achieve, you don't show the input to you transform (although from the tag-names "table", "tr", "td", I'm guessing a html-formatted table).
You seem confused by some xslt-concepts:
the xsl:copy-of-tag copies a nodeset (in your case: the contents of the $transforms-variable) to the output
the xsl:copy-tag copies the current tag (in your case, a tr-tag, since that is what is matched by the template) to the output
Also, please note that:
position() will return the relative position of the current node (your tr) within its parent, maybe that is what you want, maybe not
$transforms/transform[#id=$id] will only match transform elements on the top level of $transforms. Use double slash // if you want to match elements on any level.
Now, for transforming the contents of the $transform-variable as you specify, inserting a new element inside an element you specify, you must create:
an identity-transform copying input to output
unless the tag is the one you are looking for, in which case you insert a new element and then copy
Since the tag you are looking for is dynamic, based on the $id-variable, this must be passed as a parameter. Based on your code, I guess you want to insert a new element inside the element having #id=$id as following-sibling.
You can create such a transform with this:
<xsl:template match="node()" mode="tx">
<!-- parameters controlling behaviour as input -->
<xsl:param name="id" />
<xsl:param name="pos" />
<!-- copies the current node -->
<xsl:copy>
<!-- copies attributes of the current node -->
<xsl:copy-of select="#*" />
<!-- if the next sibling with tag transform has id=$id, insert a new element -->
<xsl:if test="following-sibling::transform[position()=1 and #id=$id]">
<transform>
<xsl:attribute name="id">
<xsl:value-of select="concat('obj_', $pos)" />
</xsl:attribute>
</transform>
</xsl:if>
<!-- call recursively, make sure to include the parameters -->
<xsl:apply-templates select="node()" mode="tx">
<xsl:with-param name="id" select="$id"/>
<xsl:with-param name="pos" select="$pos" />
</xsl:apply-templates>
</xsl:copy>
</xsl:template>
Note that I set a mode on this transform to be able to control when it is being called (I just want it called in specific circumstances, not on all input).
This can be called from your transform matching tr like this:
<xsl:template match="tr">
<xsl:variable name="param" select="$table//tr/td[2]" />
<xsl:variable name="id" select="concat('b_',$param)" />
<xsl:apply-templates select="$transforms" mode="tx">
<xsl:with-param name="id" select="$id"/>
<xsl:with-param name="pos" select="position()" />
</xsl:apply-templates>
</xsl:template>
A fully working example available here: http://xsltransform.net/bwdwsA/1